Coil for electromagnets and insulating material therefor.



No. 677,862. Patented July 9, |908.

E. F. DWYER.

COIL FUR ELECTROMAGNETS AND INSULATING MATERIAL THEREFDR.

(Application led Hay 14, 1900.) (No Model.)

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COIL FOR ELECTROMAGNETS AND INSULATING MATERIAL THEREFOR.

SPECIFICATION forming part of llfnetters Patent No. 677,862, dated July 9, 1901.

Application filed May 14, 1900. Serial No. 16,602. (No model.)

To all whom t may concern: l

Be it known that I, ELMER F. DWYER, a citizen of the United States, residing at Iiynn, in the county of Essex and State of Massachusetts, have invented certain newr and useful Improvements in Coils for Electromagnets and Insulating Material Therefor; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to an improvement in coils for electroni agn ets and insulating material therefor.

Owing to the relative cheapnes's ot' non-insulated wires as com pared with the insulated wires ordinarily used in the manufacture of electromagnet-coils, itis desirable, if possible, to use the non-insulated wire in constructing such coils, and several forms of such coils have heretofore been devised. In one form a bare wire is embedded in an insulating enameling substance applied to the wire during the winding and afterward hardened. In another form the coil is constructed by winding upon a core a bare wire and an insulatingthread, the convolutions of whichalternate, adjacent layers of the wire being insulated by means of interposed sheets of insulating material.

The object of my invention is to improve the construction of such coils, and, further, to produce a coil which shall be of a predetermined size, which shall have certain predetermined electrical properties, and which shall be of simple construction and high efficiency.

By my invention I am enabled to produce any number ofhcoils of uniform size and resistance without any special precautions on the part of the workman in assembling the parts. This feature of my invention is of value in the manufacture of electromaguets of a certain size-and resistance by the wholesale, as is necessary in some classes of electrical work.

In constructing a coil according to my invention I may and preferably do employ one or more flexible sheets of insulating material provided with a series of parallel Wire-re? ceiving grooves, and this insulating material.

I consider to be an important feature of my invention. The use of these flexible sheets is not, however, imperative, as the coil can be otherwise constructed.

In the illustrated embodiment of my invention shown in the accompanying drawings, Figure l represents in longitudinal section a coil constructed according to my iuvention, and Fig. 2 represents in plan view a strip of insulating material embodying a feature of my invention.

In the drawings, A represents a strip of insulating material composed of any suitable insulating substance or substances, which will render the strip sufficiently flexible to lend itself to the manipulations necessary in forming the coil to be described. The surface of the strip is provided with a series of parallel grooves B, formed in any desired manner in or on the surface of the strip and extending longitudinallythereof. The upper and lower margins of the strip may be left plain, as shown, for a purpose which will appear hereinafter.

Extending transversely across the strip A at intervals and intersecting the longitudinal grooves are grooves C.

The manner in which the sheet or strip of insulating material is employed in constructing a helix for an electromagnet will be obvious from Fig. 1. A sheet of the grooved insulating material cut to proper length is wrapped around the magnet-core or a mandrel of the same diameter as the core, the ends of the strip abutting and the end of one groove registering with the groove next in advance. The series of parallel grooves in the sheet are thus converted into a continuous spiral groove having a number of convolutions corresponding to the number of parallel grooves in the sheet. In lthis spiral groove a non-insulated conductor, such as a bare copper wire D, is laid, the convolutions of the conductor being retained in position by the walls of the groove and insulated from each other by the material of the Walls or by an intervening air-space in case the walls are low as compared with the diameter of the conductor. A second sheet of the grooved insulating material is now wrapped about the first sheet and the coiled conductor thereon, being secured thereto at the margin in any suitable manner, as by the nails E.

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wire D having been passed between the abutting edges of the sheet is now wound in the spiral groove of the second sheet and other sheets added until t-he number oi' superposed layers is sufficient to form a coil of the desired diameter. To complete the coil, a sheet of insulating material F is wrapped around the outer grooved sheet and its layer of noninsulated conductor and secured thereto, as by the nails E.

In the coil as completed each layer of insulating material will have one or more ventilating-grooves C, extending to the end surfaces of the coil and intersecting the grooves carrying the conductor. By this means the air contained in and between the grooves on expanding by reason of the heat generated by the coil is allowed to escape, thus preventing any displacement or warping of the insulating material. By this means also the heat generated in the conductor will be dissipated, thus enabling the number of layers to be increased or adapting the helix for heavy cur rents without liability to injury.v

It desired, the thickness of the sheets A may be increased to correspond tothe difference of potential between the different layers of the conductor. The sheets of insulating material may be so prepared that when formed into a coil their edges will form a smooth-iinished end to the coil, or the overlapping edges of the sheets may be trimmed in any suitable manner alier the coil is otherwise complete. It will be noted that the completed coil is formed ot but two elements-the insulating material and the conductorno spools with ends attached thereto for retaining the conductor in position being necessary. By having the marginal surfaces ot' the sheets free from grooves a solid end for the coil is se cured. This is not, however, essential to my invention considered in its broader aspects, as a serviceable coil can be constructed in which such marginal surfaces are not present.

It will be seen that by my invention I produce a coil which contains a certain known number of turns, which is of a certain definite size, and which has a certain resistance. By having the sheets of insulating material cut to the proper length any number of coils may 1 be constructed, which will be precisely alike as to size and electrical properties. This feature of my invention I consider of value, as before stated.

In the above description I have referred to my improved coil as being made up of a noninsulated conductor and flexible grooved sheets of insulating material. In this connection it will be noted, however, that many features of my invention do not depend upon the use of such sheets. It will be observed that the coil as completed consists of one or more layers of insulating material provided with wire-retaining grooves, with a conductor laid in said grooves and held in position thereby, and this I consider to be the essential feature of this part of my invention.

The sheet of insulating material shown in the drawings embodies my invention in the best form at present known tome. This sheet can be readily molded or otherwise formed from Well-known insulating materials. The Walls of the grooves are integral with the sheet and of a depth substantially the diameter oli the wire, so that the wires lit the grooves closely, leaving very little air-space. Vhile, however, I have shown in the drawings an integral sheet of insulating material having formed therein a series of parallel grooves, I do not wish to be understood as limiting my invention specifically thereto, as my invention, considered in its broadest aspect, contemplates a sheet of material provided with parallel wire-receiving grooves formed in any desired manner. It is also to be understood that my invention is not limited to a sheet of material provided willi parallel wire-receiv ing grooves upon one surface only.

Having thus described myinvention, what I claim as new, and desire to secure by Letters Patent, is-

l. A coil for an electromagnet, having, in combination, one or more layers of grooved insulating material and a conductor laid in said grooves and held in position thereby, sub stantially as described.

2. A coil for an electromagnet, having, in

' combination, superimposed sheets of groovcd flexible insulating material, provided with marginal surfaces free from saidgrooves, means for securing the sheets together at their margins, and a conductor positioned in the grooves, substantially as described.

3. A coil for an electromagnet, having, in combination, a coiled conductor and an insu* lating material provided with a Ventilating groove intersecting the convolutions of the 1 conductor, substantially as described.

4l. An article of manufacture, consisting of a flexible sheet of insulating material, provided upon its surface with a series of parallel wire-receiving grooves and a groove or grooves intersecting said grooves, substan tially as described.

5. A coil for an electromagnet, having, in combination, superimposed sheets of flexible insulating material,each sheet being provided with a series or" parallel grooves, the end of one groove registering with the end of the next adjacent groove at the abutting edges of the sheet to form a continuous groove and a conductor laid in said grooves and held in position thereby, substantially as described.

In testimony whereof I ai'lix my signature in presence of two witnesses.

ELMER F. DIVYER.

I'Vitnesses:

HORACE VAN EvnnnN, ALFRED Il. HILDnn'rH.

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